Identification of aminoglycoside-modifying enzymes by susceptibility testing: Epidemiology of methicillin-resistant Staphylococcus aureus in Japan

Citation
T. Ida et al., Identification of aminoglycoside-modifying enzymes by susceptibility testing: Epidemiology of methicillin-resistant Staphylococcus aureus in Japan, J CLIN MICR, 39(9), 2001, pp. 3115-3121
Citations number
38
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Clinical Immunolgy & Infectious Disease",Microbiology
Journal title
JOURNAL OF CLINICAL MICROBIOLOGY
ISSN journal
0095-1137 → ACNP
Volume
39
Issue
9
Year of publication
2001
Pages
3115 - 3121
Database
ISI
SICI code
0095-1137(200109)39:9<3115:IOAEBS>2.0.ZU;2-8
Abstract
A multiple-primer PCR was used to identify genes encoding aminoglycoside-mo difying enzymes in 381 clinical isolates of methicillin-resistant Staphyloc occus aureus (MRSA). The technique used three sets of primers delineating s pecific DNA fragments of the aph(3')-III, ant(4')-I, and aac(6')-aph(2") ge nes, which influence the MICs of gentamicin, tobramycin, and lividomycin. I solates with none of the three genes detected were susceptible to all three agents. Isolates with the aph(3')-III gene showed resistance to lividomyci n (MIC > 1,024 mug/ml), and those with the ant(4')-I gene were resistant to tobramycin (MIC greater than or equal to 8 mug/ml). Isolates with only the aac(6')-aph(2") gene were resistant to gentamicin (MIC greater than or equ al to 8 mug/ml) and tobramycin in decreasing order; those with both the ant (4')-I and aac(6')-aph(2") genes also were resistant to gentamicin and tobr amycin, but in increasing order. Susceptibility testing, then, could detect specific genes. In 381 Japanese MRSA isolates, the ant(4')-I, aac(6')-aph( 2"), and aph(3') -III genes were prevalent in 84.5, 61.7, and 8.9%, respect ively. Isolates with only the ant(4')-I gene had coaguIase type II or III, but isolates with both the ant(4')-I and aac(6')-aph(2") genes included all coagulase types. Most isolates with coagulase type IV or VII carried the a ac(6')-aph(2") gene. Of the MRSA isolates with ant(4')-I and/or aac(6')-aph (2") genes, 97% were resistant to aminoglycosides in clinical use, but a ne w aminoglycoside, arbekacin, had excellent activity against these isolates.